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Compact and fast implementations of digital Rayleigh and Ricean variate generators are presented. Polynomial curve fitting is utilized along with a combination of logarithmic and uniform domain segmentation to provide accuracy, co...
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Compact and fast implementations of digital Rayleigh and Ricean variate generators are presented. Polynomial curve fitting is utilized along with a combination of logarithmic and uniform domain segmentation to provide accuracy, compactness and fast variate generation. A typical instantiation of the proposed Rayleigh generator occupies 124 ($1%) of the configurable slices, two dedicated multipliers ($1%), and one on-chip block memory ($ 1%) of a Xilinx Virtex-5 field-programmable gate array (FPGA) and operates at 317 MHz, generating 317 million Rayleigh variates per second. The Ricean variate generator implementation on the same device utilizes 366 ($ 1%) of the logical slices, three on-chip block memories ( $1%), and 11 (2.8%) of the dedicated multipliers. The application of the Rayleigh and Ricean variate generators is demonstrated in a FPGA-based bit error rate simulator that measures at hardware speeds the symbol error rate performance of a typical wireless communication system over Rayleigh and Ricean fading channels.
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This study examined 2 methodological issues that might influence the fading affect bias (FAB).The FAB occurs when people report that the affective intensity associated with unpleasantevents decreases over time more than the intens...
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This study examined 2 methodological issues that might influence the fading affect bias (FAB).The FAB occurs when people report that the affective intensity associated with unpleasantevents decreases over time more than the intensity of positive events. In the experiments re-ported here we investigated the FAB using a between-subject design (Experiments 1a and 1 b)and manipulated the order of the ratings (past and current) used to measure the FAB (Experi-ment 2). In each case, we observed a strong FAB effect, suggesting that it is not solely a functionof the research design or the order of the intensity ratings. Thus, the FAB is a robust phenomenonthat appears in many different situations.
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Acoustics Communication finds numerous applications and growing in popularity, complexity and capabilities. Acoustic waves propagation plays important role for effective Underwater Wireless Communication. Underwater acoustic signa...
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Acoustics Communication finds numerous applications and growing in popularity, complexity and capabilities. Acoustic waves propagation plays important role for effective Underwater Wireless Communication. Underwater acoustic signals used for communications are prone to fading. Unlike radio waves, acoustic waves experience several losses like; signal loss, fading, path loss, and Doppler spread in water. To model any communication medium, mathematical tools play a vital role. Real-time underwater wireless network applications require good Quality-of-Service guarantees such as low packet delay and small backlog. Modern communication networks are growing rapidly and measuring its QoS needs a specialized analytical tools. To overcome these, Stochastic Network Calculus (SNC) has given rise to the optimism that it can emerge as an elegant mathematical modelling tool for assessing current network performance especially for use in underwater communication. While SNC is a relatively new theory, it is gaining increasing interest and popularity and researchers have also started applying SNC to performance analysis of various systems. In this work, we have developed an underwater acoustic wireless channel subjected to different fading techniques such as; Rayleigh, Rician, Nakagami, Weibull, AWGN, Gilbert-Elliot. In this work, we have derived stochastic service guarantees for delay requirements, violation probabilities, delay bound and traffic burstiness in the acoustic Physical channel. Using this model we have also derived the stochastic performance for delay and backlog bounds.
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This paper investigates the asymptotic error rate behaviour for noncoherent OOK signalling scheme in the presence of nakagami-m fading. A transcendental equation to compute the optimum threshold level is also derived. Compari- son...
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This paper investigates the asymptotic error rate behaviour for noncoherent OOK signalling scheme in the presence of nakagami-m fading. A transcendental equation to compute the optimum threshold level is also derived. Compari- son on trends in optimum threshold level and its corresponding ratio of the Mark and Space error probabilities between different channels are presented.
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Quadrature space shift keying (QSSK) modulation combined with cooperative relaying improves the reliability in communication and enhances the overall spectral efficiency. Here, QSSK scheme is analyzed for multiple-input multiple-o...
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Quadrature space shift keying (QSSK) modulation combined with cooperative relaying improves the reliability in communication and enhances the overall spectral efficiency. Here, QSSK scheme is analyzed for multiple-input multiple-output (MIMO) wireless communication system with dual-hop amplify-and-forward (AF) relaying systems over asymmetric mixed Rayleigh/Rician and symmetric Nakagami-m/Nakagami-m fading channels. Analytical expressions for cumulative distribution function (CDF) of the end-to-end signal-to-noise ratio are derived and used to evaluate the average bit error probability (ABEP) of QSSK modulation in mixed asymmetric and symmetric fading channels. The obtained ABEP expression is in the form of Whittaker function, which can be numerically evaluated using its numerical or series representation. Numerical and simulation results are presented to illustrate the impact of fading parameters on the system performance.
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The fading phenomenon in mobile communications is mainly a stochastic process and plays an essential role in the reliability and stability of the systems. The frequency bands currently in use it is reasonably well characterized an...
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The fading phenomenon in mobile communications is mainly a stochastic process and plays an essential role in the reliability and stability of the systems. The frequency bands currently in use it is reasonably well characterized and described. With the use of mmW, only experimental, theoretical models are being proposed; there is no unanimity regarding a model that effectively contemplates the phenomenon in this spectrum range. Some studies suggest the traditional models applied to the frequencies in use; Rician and Rayleigh are the main ones. This study aims to advance and compare, with accepted models, a broader statistical model that overcomes the limitations of the current models. It will be analyzed and compared a model using the Nakagami-m distribution covering a greater range of possibilities, given the low spreading capacity of mmW and the need for links almost always LOS situation in which the Rician model fails.
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We present an ultracompact and fast hardware simulator for Rayleigh and Rician fading channels. To ensure numerical robustness and an efficient mapping onto hardware, the fading simulator uses the sum-of-sinusoids technique with $...
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We present an ultracompact and fast hardware simulator for Rayleigh and Rician fading channels. To ensure numerical robustness and an efficient mapping onto hardware, the fading simulator uses the sum-of-sinusoids technique with $N = 32$ sinusoids added up to model each fading path. Fading samples are generated at a low rate and then are passed to an interpolator, which computes the final samples at the desired baseband rate. We propose a new time-multiplexed datapath that uses a differential approach. Instead of directly generating the fading samples, the datapath generates the discrete difference between fading samples. The proposed simulator is so compact that an entire 4 $times$ 4 multiple-input–multiple-output (MIMO) fading channel can be implemented on a small fraction of a single field-programmable gate array (FPGA). On a Xilinx Virtex-4 XC4VLX200-11 FPGA, up to 1184 different paths can be simultaneously implemented while generating 1184 $times$ 342 million 2 $times$ 16-bit complex-valued fading samples per second.
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An original physical model for the spectrum and autocorrelation of shadow fading is derived using lumped circuit theory. While realizing much greater generality, the model specializes to previous empirical models and also unifies ...
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An original physical model for the spectrum and autocorrelation of shadow fading is derived using lumped circuit theory. While realizing much greater generality, the model specializes to previous empirical models and also unifies the previous models. The model is tested using published measurement data, and shows excellent fits to the data. Conditions under which the model becomes a Gaussian titter response are proved. The new model is able to explain intuitively, previously observed but unexplained shadowing behavior. The accuracy and flexibility of the model surpasses that of all previous shadowing models.
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There are two approaches well known in the literature for reducing the complexity in averaged
performance analyses of wireless communications systems (i.e., for alleviating the computational
difficulty in averaged performance ev...
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There are two approaches well known in the literature for reducing the complexity in averaged
performance analyses of wireless communications systems (i.e., for alleviating the computational
difficulty in averaged performance evaluations). The first method, known as the moment generating
function MGF-based approach, aims to convert the instantaneous performance measure into an
exponential integration or a certain sum of exponential functions of different scales. The second
approach, which is the focus of this article, aims to convert the exact probability density function PDF
and cumulative distribution function CDF of fading distributions into the sum of exponential functions of
various scales. As such, we propose weighted sum of exponential functions as alternative closed-form
approximations for the PDF and CDF of gamma distribution, η − μ distribution, and κ − μ shadowed
distribution with integer fading parameters, and we present how these proposed expressions can
be easily applied to the performance analysis of wireless communication systems operating over
Nakagami-m fading channels, η − μ fading channels, and κ − μ shadowed fading channels.
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In this paper, we consider the ergodic channel capacity (ECC) of several generalized fading channels for a mobile user that moves inside a coverage area according to the random waypoint (RWP) mobility model. The ECC with RWP mobil...
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In this paper, we consider the ergodic channel capacity (ECC) of several generalized fading channels for a mobile user that moves inside a coverage area according to the random waypoint (RWP) mobility model. The ECC with RWP mobility provides the average capacity of a mobile receiver taking into account the probability density function (PDF) of the distance between the user and the transmitting antenna, the path loss exponent and the fading channel. It turns out that the ECC in a mobile environment can be written in terms of the corresponding ECC in the static case. Therefore, we use analytical expressions of the ECC of different generalized fading models for the static channel to derive the corresponding analytical expressions for the ECC in the mobile case. Asymptotic expressions, in the high signal-to-noise ratio (SNR) regime, are also provided that quickly converge to the exact ones. Monte Carlo simulation is also used to show the validity of the derived expressions. The analytical exact and asymptotic expressions enable the system designer to quantify the effect of different physical channel and mobility parameters on the attained average capacity of generalized fading channels.
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